ipv6 dhcp bindings - same address multiple times

jni · ‎11-08-2017

Hello

Any suggestions as to what I might do wrong? I have some switches with multiple L3 VLANs with IPv6 enabled (SLAAC). Everything is working, however, when I look at my IPv6 dhcp bindings, I get A LOT of clients (duplicates). It is essentially creating a sort of "memory leak"

configuration

ipv6 unicast-routing
ipv6 dhcp pool v6-pool
 dns-server xxxx:xxx:3AC::8888
 dns-server xxxx:xxx:3AC::8844
 domain-name domain.com
!
interface FastEthernet0/40
 switchport access vlan 140
 switchport mode access
 no logging event link-status
 no snmp trap link-status
 no mdix auto
 spanning-tree portfast
!
interface Vlan140
 ip address 10.184.140.1 255.255.255.0
 ip access-group DEFAULT-IN in
 ipv6 address xxxx:xxx:3AC:140::1/64
 ipv6 nd autoconfig prefix
 ipv6 nd other-config-flag
 ipv6 dhcp server v6-pool
 ipv6 traffic-filter v6-in in

show commands

sw1#sh ipv6 dhcp pool
DHCPv6 pool: v6-pool
  DNS server: xxxx:xxx:3AC::8888
  DNS server: xxxx:xxx:3AC::8844
  Domain name: domain.com
  Active clients: 336751     <---- note there should be maybe max. 500 clients

sw1#sh ipv6 dhcp bind FE80::52C7:BFFF:FE76:52D7
Client: FE80::52C7:BFFF:FE76:52D7 (Vlan140)
  DUID: 000100012195A6F550C7BF7652D7
  IA NA: IA ID 0x00022D70, T1 0, T2 0
Client: FE80::52C7:BFFF:FE76:52D7 (Vlan140)
  DUID: 000100012195A4F450C7BF7652D7
  IA NA: IA ID 0x00022B6F, T1 0, T2 0
Client: FE80::52C7:BFFF:FE76:52D7 (Vlan140)
  DUID: 000100012195A8F650C7BF7652D7
  IA NA: IA ID 0x00022F71, T1 0, T2 0
Client: FE80::52C7:BFFF:FE76:52D7 (Vlan140)
  DUID: 000100012195A2F350C7BF7652D7
  IA NA: IA ID 0x0002296E, T1 0, T2 0
Client: FE80::52C7:BFFF:FE76:52D7 (Vlan140)
  DUID: 000100012195A0F250C7BF7652D7
  IA NA: IA ID 0x0002276D, T1 0, T2 0
Client: FE80::52C7:BFFF:FE76:52D7 (Vlan140)
  DUID: 000100012195A7E450C7BF7652D7
  IA NA: IA ID 0x00022E5F, T1 0, T2 0
Client: FE80::52C7:BFFF:FE76:52D7 (Vlan140)
.....<some clients have A LOT of entries>

Thank you in advance :o)

jni · ‎11-10-2017

Forgot to mention the platform: WS-C3560-48TS Version 15.0(2)SE11. I have tried different versions without any luck. Anyone have any ideas as to what is wrong?

Tinashe Ndhlovu · ‎11-11-2017

Hi, i haven't encountered this issue before but if you may, please post the output of the following command:

show ipv6 dhcp binding

I know that will probably be a lot of output but just send the details relating to one entry.

I am throwing spaghetti at the wall here but i think your issue is related to the preferred lifetime values causing the IA NA to change each time a PC boots up or reconnects to the network and thus the DCHP server thinks its a new request and sends out DNS info again... but let me not speculate, send the output and lets take it from there

jni · ‎11-13-2017

Hello.

Thank you for your reply. You are right, a sh ipv6 dhcp bindings would be massive. As of now, I have 62301 "active" clients.

sw1#sh ipv6 dhcp pool
DHCPv6 pool: v6-pool
  DNS server: xxxx:xxx:3AC::8888
  DNS server: xxxx:xxx:3AC::8844
  Domain name: domain.com
  Active clients: 62301

...of course this is wrong and is due to multiple duplicate entries.

I can give you a complete output of a single host, but that would also be massive. I've copied some of the output for a single host (all in all it went on for 36000 lines for this output - in other words this host alone takes about 12000 entries). There are a lot of clients who have between 8000-14000 entries each.

sw1#sh ipv6 dhcp binding FE80::8616:F9FF:FEE4:D203
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 000100012195D36A8416F9E4D203
  IA NA: IA ID 0x0034E025, T1 0, T2 0
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 000100012195D86A8416F9E4D203
  IA NA: IA ID 0x0034E526, T1 0, T2 0
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 00010001219668698416F9E4D203
  IA NA: IA ID 0x00357524, T1 0, T2 0
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 0001000121966D698416F9E4D203
  IA NA: IA ID 0x00357A25, T1 0, T2 0
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 00010001219672698416F9E4D203
  IA NA: IA ID 0x00357F25, T1 0, T2 0
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 000100012196C5698416F9E4D203
  IA NA: IA ID 0x0035D224, T1 0, T2 0
......
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 00010001219B949B8416F9E4D203
  IA NA: IA ID 0x003AA157, T1 0, T2 0
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 00010001219B999B8416F9E4D203
  IA NA: IA ID 0x003AA657, T1 0, T2 0
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 00010001219BF19B8416F9E4D203
  IA NA: IA ID 0x003AFE56, T1 0, T2 0
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 00010001219BF69B8416F9E4D203
  IA NA: IA ID 0x003B0357, T1 0, T2 0
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 00010001219BFB9B8416F9E4D203
  IA NA: IA ID 0x003B0857, T1 0, T2 0
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 00010001219C009C8416F9E4D203
  IA NA: IA ID 0x003B0D57, T1 0, T2 0
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 00010001219C1C9C8416F9E4D203
  IA NA: IA ID 0x003B2957, T1 0, T2 0
Client: FE80::8616:F9FF:FEE4:D203 (Vlan178)
  DUID: 00010001219C219C8416F9E4D203
  IA NA: IA ID 0x003B2E58, T1 0, T2 0

As I've said before, I have tried different IOS versions (both 12.2, 12.3 and 15.x train), but with the same result. So any help would be appreciated :o)

JakeH · ‎03-06-2018

Hi @jni

I am facing the exact same issue.

Did you ever find a solution for this?

Best regards, Jacob